B Flat is exactly as cozy and cavernous as a basement cocktail lounge should be. But while the locations may be underground, the drinks are definitely top level. Helmed by the original bartenders from Angel’s Share in the East Village, one of the best-respected originators of Manhattan’s serious mixology scene, the TriBeCa lounge has a decidedly Tokyo vibe. Low music, dim lighting, and deep couches make it a perfect date spot, and live jazz music from 8pm to 11pm on Monday and Wednesday nights is an added treat. While the focus is on the cocktails and ambiance, the bar snacks are ideal for sharing, and delicious.